Determination of carbamazepine and carbamazepine 10,11-epoxide in human plasma by tandem liquid chromatography-mass spectrometry with electrospray ionisation

A sensitive method for the determination of carbamazepine and carbamazepine 10,11-epoxide in plasma is described, using high-performance liquid chromatographic separation with tandem mass spectrometry. Samples were purified using liquid-liquid extraction and separated on a Phenomenex Luna C18 5 microm. 150 x 2 mm column with a mobile phase consisting of acetonitrile, methanol and formic acid (0.1%) (10:70:20, v/v). Detection was performed by a Micromass Quattro Ultima mass spectrometer in the MRM mode (LC-MS-MS) using electro spray ionisation (ESI+), monitoring the transition of the protonated molecular ion for carbamazepine at m/z 237.05 and carbamazepine 10,11-epoxide at m/z 253.09 to the predominant ions of m/z 194.09 and 180.04, respectively. The mean recovery was 95% for carbamazepine and 101% for carbamazepine 10,11-epoxide, with a lower limit of quantification of 0.722 ng/ml for carbamazepine and 5.15 ng/ml for carbamazepine 10,11-epoxide, when using 0.5 ml plasma. This high-throughput method was used to quantify 230 samples per day, and is sufficiently sensitive to be employed in pharmacokinetic studies.     

Enantioselective LC/MS method for the determination of an antimalarial agent Fenozan B07 in dog plasma

A chiral liquid chromatography/mass spectrometry (LC/MS) bioanalytical procedure has been developed for the analysis of the antimalaric agent Fenozan B07 in dog plasma. Normal-phase chromatography involving a phenylcarbamate derivative of cellulose coated on silica gel as the chiral stationary phase was used to resolve (-)-(S,S)-B07 from (+)-(R,R)-B07. The enantiomers were detected by a mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) interface operated in the negative ion mode. A mass spectrum, characterized by a base peak of m/z 285, was obtained for each enantiomer. The m/z 285 ion was very specific for the analysis of both enantiomers in the plasma. The selected ion monitoring analysis of the plasma samples was therefore performed at m/z 285 for quantitative purposes. The enantiomers were extracted from the plasma in a basic medium and purified by solid-phase extraction using a hydrophilic-lipophilic balanced sorbent. A lower limit of quantification of 2 ng/mL in plasma was achieved for both enantiomers. The quantitative procedure reported in this study was highly specific and sensitive, and was validated according to the FDA guidance on bioanalytical method validation.     

High-performance liquid chromatography for the determination of 3-n-butylphthalide in rat plasma by tandem quadrupole mass spectrometry: application to a pharmacokinetic study

A rapid, sensitive and specific high performance liquid chromatography-electrospray ionization tandem quadrupole mass spectrometry (HPLC-MS/MS) method was developed and validated for the determination of 3-n-butylphthalide in rat plasma. Following protein precipitation with acetonitrile, 3-n-butylphthalide and glipizide (internal standard, I.S.) were separated using a gradient elution program on a C18 column and detected by mass spectrometry in positive ion mode with the multiple reaction monitoring (MRM) mode using the respective precursor to product ion combinations of m/z 191/145 for 3-n-butylphthalide and m/z 446/321 for glipizide, respectively. The total chromatographic running time was 2.5 min. The method was linear over the concentration range of 11.14-3480.00 ng/mL, using as little as 100 microL plasma. The lower limit of quantification (LLOQ) was 5.57 ng/mL. Finally, the method was successfully used to support a preclinical pharmacokinetic study of 3-n-butylphthalide in rats following intravenous administration.     

Determination of fexofenadine in human plasma and urine by liquid chromatography-mass spectrometry

A sensitive method was developed to determine fexofenadine in human plasma and urine by HPLC-electrospray mass spectrometry with MDL 026042 as internal standard. Extraction was carried out on C18 solid-phase extraction cartridges. The mobile phases used for HPLC were: (A) 12 mM ammonium acetate in water and (B) acetonitrile. Chromatographic separation was achieved on a LUNA CN column (10 cm x 2.0 mm I.D., particle size 3 microm) using a linear gradient from 40% B to 60% B in 10 min. The mass spectrometer was operated in the selected ion monitoring mode using the respective MH+ ions, m/z 502.3 for fexofenadine and m/z 530.3 for the internal standard. The limit of quantification achieved with this method was 0.5 ng/ml in plasma and 1.0 ng in 50 microl of urine. The method described was successfully applied to the determination of fexofenadine in human plasma and urine in pharmacokinetic studies.     

Determination of duloxetine in human plasma by liquid chromatography with atmospheric pressure ionization-tandem mass spectrometry and its application to pharmacokinetic study

A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometry (LC-MS-MS) method is described for the determination of duloxetine in human plasma. Duloxetine was extracted from plasma using methanol and separated on a C18 column. The mobile phase consisting of a mixture of acetonitrile and 5mM ammonium acetate (45:55, v/v, pH 3.5) was delivered at a flow rate of 0.3 ml/min. Atmospheric pressure ionization (API) source was operated in positive ion mode. Multiple reaction monitoring (MRM) mode using the transitions of m/z 298.1-->m/z 44.0 and m/z 376.2-->m/z 123.2 were used to quantify duloxetine and internal standard (I.S.), respectively. The linearity was obtained over the concentration range of 0.1-50.0 ng/ml and the lower limit of quantitation (LLOQ) was 0.1 ng/ml. This method was successfully applied to pharmacokinetic study of a duloxetine formulation product after oral administration to healthy human subjects.     

Development and validation of a high performance liquid chromatography-tandem mass spectrometry for the determination of etodolac in human plasma

A simple and specific method using a one-step liquid-liquid extraction (LLE) with butyl acetate followed by high performance liquid chromatography (HPLC) coupled with positive ion electrospray ionization tandem mass spectrometry (ESI-MS/MS) detection was developed for the determination of etodolac in human plasma, using indomethacin as an internal standard (IS). Chromatographic separation was performed isocratically using a Capcellpak MGII C(18) column with 65% acetonitrile and 35% water containing 10mM ammonium formate (adjusted to pH 3.5 with formic acid). Acquisition was performed in multiple reaction monitoring (MRM) mode by monitoring the transitions: m/z 287.99>172.23 for etodolac and m/z 357.92>139.01 for IS. The method was validated to determine its selectivity, linearity, sensitivity, precision, accuracy, recovery and stability. The limit of quantitation (LLOQ) was 0.1microg/mL with a relative standard deviation of less than 15%. The devised method provides an accurate, precise and sensitive tool for determining etodolac levels in plasma.     

Determination of zolmitriptan in human plasma by liquid chromatography-tandem mass spectrometry method: application to a pharmacokinetic study

A sensitive and selective liquid chromatography-tandem spectrometry method for the determination of zolmitriptan was developed and validated over the linearity range 0.05-30 ng/ml with 0.5 ml of plasma using diphenhydramine as the internal standard. Liquid-liquid extraction using a mixture of diethyl ether and dichloromethane was used to extract the drug and the internal standard from plasma. The mass spectrometer was operated under the selected reaction monitoring (SRM) mode using the atmospheric pressure chemical ionization (APCI) technique. The instrument parameters were optimized to obtain 3.0 min run time. The mobile phase consisted of acetonitrile-water-formic acid (70:30:0.5), at a flow rate of 0.5 ml/min. In positive mode, zolmitriptan produced a protonated precursor ion at m/z 288 and a corresponding product ion at m/z 58. And internal standard produced a protonated precursor ion at m/z 256 and a corresponding product ion at m/z 167. The inter- and intra-day precision (%R.S.D.) were less than 8.5% and accuracy (%error) was less than -2.5%. The method had a lower limit of quantification of 0.05 ng/ml for zolmitriptan, which offered increased sensitivity and selectivity of analysis, compared with existing methods. The method was successfully applied to a pharmacokinetic study of zolmitriptan after an oral administration of 5 mg zolmitriptan to 20 healthy volunteers.     

Sensitive quantification of omeprazole and its metabolites in human plasma by liquid chromatography-mass spectrometry

A sensitive method was developed for the simultaneous determination of omeprazole and its major metabolites 5-hydroxyomeprazole and omeprazole sulfone in human plasma by HPLC-electrospray mass spectrometry. Following liquid-liquid extraction HPLC separation was achieved on a ProntoSil AQ, C18 column using a gradient with 10 mM ammonium acetate in water (pH 7.25) and acetonitrile. The mass spectrometer was operated in the selected ion monitoring mode using the respective MH(+) ions, m/z 346 for omeprazole, m/z 362 for 5-hydroxy-omeprazole and omeprazol-sulfone and m/z 300 for the internal standard (2-{[(3,5-dimethylpyridine-2-yl)methyl]thio}-1H-benzimidazole-5-yl)methanol. The limit of quantification (LOQ) achieved with this method was 5 ng/ml for 5-hydroxyomeprazole and 10 ng/ml for omeprazole and omeprazole-sulfone using 0.25 ml of plasma. Intra- and inter-assay variability was below 11% over the whole concentration range from 5 to 250 ng/ml for 5-hydroxyomeprazol and from 10 to 750 ng/ml for omeprazole and omeprazole-sulfone. The method was successfully applied to the determination of pharmacokinetic parameters of esomeprazole and the two major metabolites after a single dose and under steady state conditions.     

Quantitative analysis of albuterol in human plasma by combined gas chromatography chemical ionization mass spectrometry

A highly sensitive and specific quantitative assay for the determination of albuterol in human plasma, based on selected ion monitoring gas chromatography chemical ionization mass spectrometry, has been developed. The [MH]+ ions from the tri-TMS derivatives of albuterol (m/z 456) and the internal standard (2H3)albuterol (m/z 459), were assayed simultaneously by selected ion monitoring. The lower limit of quantitation is 0.25 ng ml-1 and the average assay precision (CV) for albuterol concentrations ranging from 0.25 ng ml-1 to 25 ng ml-1 is approximately 4%. This method is currently being employed for the routine quantitation of albuterol in plasma following the administration of doses therapeutically effective to man.     

Simultaneous determination of fixed dose combination of nebivolol and valsartan in human plasma by liquid chromatographic-tandem mass spectrometry and its application to pharmacokinetic study

A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometry method is described for the simultaneous determination of nebivolol and valsartan in human plasma. Nebivolol and valsartan were extracted from plasma using acetonitrile and separated on a C18 column. The mobile phase consisting of a mixture of acetonitrile and 0.05 mM formic acid (50:50 v/v, pH 3.5) was delivered at a flow rate of 0.25 ml/min. Atmospheric pressure ionization (API) source was operated in both positive and negative ion mode for nebivolol and valsartan, respectively. Selected reaction monitoring mode (SRM) using the transitions of m/z 406.1-->m/z 150.9; m/z 434.2-->m/z 179.0 and m/z 409.4-->m/z 228.1 were used to quantify nebivolol, valsartan and internal standard (IS), respectively. The linearity was obtained over the concentration range of 0.01-50.0 ng/ml and 1.0-2000.0 ng/ml and the lower limits of quantitation were 0.01 ng/ml and 1.0 ng/ml for nebivolol and valsartan, respectively. This method was successfully applied to the pharmacokinetic study of fixed dose combination (FDC) of nebivolol and valsartan formulation product after an oral administration to healthy human subjects.     

Liquid chromatography tandem mass spectrometry method for simultaneous determination of metoprolol tartrate and ramipril in human plasma

A simple, rapid, sensitive and specific liquid chromatography-tandem mass spectrometry method was developed and validated for quantification of metoprolol tartrate (MT) and ramipril, in human plasma. Both the drugs were extracted by liquid-liquid extraction with diethyl ether-dichloromethane (70:30, v/v). The chromatographic separation was performed on a reversed-phase C8 column with a mobile phase of 10 mM ammonium formate-methanol (3:97, v/v). The protonated analyte was quantitated in positive ionization by multiple reaction monitoring with a mass spectrometer. The method was validated over the concentration range of 5-500 ng/ml for metoprolol and ramipril in human plasma. The precursor to product ion transitions of m/z 268.0-103.10 and m/z 417.20-117.20 were used to measure metoprolol and ramipril, respectively.     

Determination of lapatinib (GW572016) in human plasma by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS)

A sensitive method for the determination of lapatinib (GW572016) in human plasma was developed using high-performance liquid chromatographic separation with tandem mass spectrometric detection. Plasma samples (100 microL) were prepared using solid phase extraction (SPE) columns, and 6.0 microL of the reconstituted eluate was injected onto a Phenomenex CuroSil-PFP 3 mu analytical column (50 mm x 2.0mm) with an isocratic mobile phase. Analytes were detected with a PE SCIEX API-365 LC-MS/MS system at unit (Q1) and low (Q3) resolution in positive multiple reaction monitoring mode (m/z 581 (precursor ion) to m/z 364 (product ion) for lapatinib). The mean recovery for lapatinib was 75% with a lower limit of quantification of 15 ng/mL (S/N=11.3, CV< or =14%). This method was validated over a linear range of 100-10,000 ng/mL, and results from a 5-day validation study demonstrated good within-day and between-day precision and accuracy. This method has been used to measure plasma lapatinib concentrations in a Phase I study in children with cancer.     

Determination of Cloretazine (VNP40101M) and its active metabolite (VNP4090CE) in human plasma by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS)

A sensitive method for the determination of Cloretazine (VNP40101M) and its metabolite (VNP4090CE) with an internal standard (ISTD) in human plasma was developed using high-performance liquid chromatographic separation with tandem mass spectrometric detection. Acidified plasma samples (500 microL) were prepared using solid phase extraction (SPE) columns, and 25 microL of the reconstituted sample was injected onto an Ascentis C18 HPLC column (3 microm, 5 cmx2.1 mm) with an isocratic mobile phase. Analytes were detected with an API-3000 LC-MS/MS System at unit (Q1) and low (Q3) resolution in negative multiple reaction monitoring mode: m/z 249.0 (precursor ion) to m/z 114.9 (product ion) for both Cloretazine (at 3.64 min) and VNP4090CE (at 2.91 min), and m/z 253.0 (precursor ion) to m/z 116.9 (product ion) for the ISTD. The mean recovery for Cloretazine (VNP40101M) and its metabolite (VNP4090CE) was greater than 87% with a lower limit of quantification of 1.0 ng/mL for Cloretazine (S/N=9.7, CV相似文献   

Determination of tamsulosin in dog plasma by liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry

A rapid, sensitive and accurate liquid chromatographic-tandem mass spectrometric method is described for the determination of tamsulosin in dog plasma. Tamsulosin was extracted from plasma using a mixture of hexane-ethyl acetate (2:1, v/v) and separated on a C18 column interfaced with a triple quadrupole tandem mass spectrometer. The mobile phase consisting of a mixture of methanol, water and formic acid (80:20:1, v/v/v) was delivered at a flow rate of 0.5 ml/min. Atmospheric pressure chemical ionization (APCI) source was operated in positive ion mode. Selected reaction monitoring (SRM) mode using the transitions of m/z 409-->m/z 228 and m/z 256-->m/z 166.9 were used to quantify tamsulosin and the internal standard, respectively. The linearity was obtained over the concentration range of 0.1-50.0 ng/ml for tamsulosin and the lower limit of quantitation was 0.1 ng/ml. For each level of QC samples, inter- and intra-run precision was less than 5.0 and 4.0% (relative standard deviation (R.S.D.)), respectively, and accuracy was within +/-0.3% (relative error (R.E.)). This method was successfully applied to pharmacokinetic study of a tamsulosin formulation product after oral administration to beagle dogs.     

Liquid chromatography-electrospray mass spectrometry determination of carbamazepine, oxcarbazepine and eight of their metabolites in human plasma

Carbamazepine (CBZ) and oxcarbazepine (OXCBZ) are both antiepileptic drugs, which are prescribed as first-line drugs for the treatment of partial and generalized tonic-clonic epileptic seizures. In this paper, a specific and sensitive liquid chromatography-electrospray ionization mass spectrometry method was described for the simultaneous determination of carbamazepine (CBZ), oxcarbazepine (OXCBZ) and eight of their metabolites [CBZ-10,11-epoxide (CBZ-EP), 10,11-dihydro-10,11-trans-dihydroxy-carbamazepine (DiOH-CBZ), 10-hydroxy-10,11-dihydroCBZ (10-OH-CBZ), 2-hydroxycarbamazepine (2-OH-CBZ), 3-hydroxycarbamazepine (3-OH-CBZ), iminostilbene (IM), acridone (AO) and acridine (AI)] in human plasma. The work-up procedure involved a simple precipitation with acetone. Separation of the analytes was achieved within 50 min using a Zorbax eclipse XD8 C8 analytical column. The mobile phase consisted of a mixture of acetonitrile-formate buffer (2 mM, pH 3). Detection was performed using a quadrupole mass spectrometer fitted with an electrospray ion source. Mass spectrometric data were acquired in single ion recording mode at m/z 237 for CBZ, m/z 180 for CBZ-EP and AI, m/z 236 for OXCBZ, m/z 237 for 10-OH-CBZ, m/z 253 for 2-OH-CBZ, 3-OH-CBZ and DiOH-CBZ, m/z 196 for AO and m/z 194 for IM. For all analytes, the drug/internal standard peak height ratios were linked via a quadratic relationship to plasma concentrations. The extraction recovery averaged 90% for CBZ, 80% for OXCBZ and was 80-105% for the metabolites. The lower limit of quantitation was 0.5mg/l for CBZ, 0.4 mg/l for OXCBZ and ranged from 0.02 to 0.3 mg/l for the metabolites. Precision ranged from 2 to 13% and accuracy was between 86 and 112%. This method was found suitable for the analysis of plasma samples collected during therapeutic drug monitoring of patients treated with CBZ or OXCBZ.     

Liquid chromatography-tandem mass spectrometry method for determination of N-acetylglucosamine concentration in human plasma

A simple, reliable and sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for quantification of N-acetylglucosamine in human plasma. Plasma samples were pretreated with acetonitrile for protein precipitation. The chromatographic separation was performed on Hypersil Silica column (150mmx2mm, 5microm). The deprotonated analyte ion was detected in negative ionization mode by multiple reaction monitoring mode. The mass transition pairs of m/z 220.3-->118.9 and m/z 226.4-->123.2 were used to detect N-acetylglucosamine and internal standard 13C6-N-acetylglucosamine, respectively. The assay exhibited a linear range from 20 to 1280ng/ml for N-acetylglucosamine in human plasma. Acceptable precision and accuracy were obtained for concentrations of the calibration standard and quality control. The validated method was successfully applied to analyze human plasma samples in a pharmacokinetic study.     

Quantitative determination of nystatin in human plasma using LC-MS after inhalative administration in healthy subjects

The antifungal polyene antibiotics nystatin was tested in a clinical trial to describe pharmacokinetics and safety after repeated administration of Nystatin "Lederle" sterile powder in healthy volunteers. To monitor the nystatin concentration-time profile in plasma we developed a sensitive method in the range of 1-100ng/ml based on liquid chromatography coupled with tandem mass spectrometry. The target substance was separated from the biological matrix on C(18) solid-phase extraction cartridges with methanol. The Chromatography was performed isocratically using a reversed phase Caltrex Resorcinearene column. The mobile phase consisted of 5mM ammonium formate buffer and acetonitrile (40:60, v/v). The mass spectrometer works with electrospray ionization in its positive selected ion monitoring (SIM) mode using the respective MH(+) ions, m/z 926.6 for nystatin and m/z 924.4 for amphotericin B as internal standard. The method validation was performed according to the demands and international criteria for validation of bioanalytical methods and was successfully applied to the quantification of nystatin in human plasma in the pharmacokinetic trial.     

Determination of dimenhydrinate in human plasma by liquid chromatography-electrospray tandem mass spectrometry: application to a relative bioavailability study

Here we present a sensitive and specific liquid chromatography-tandem mass spectrometric method for the quantification of dimenhydrinate (I) in human plasma. Sample preparation is conducted using citalopram (II) addition as an internal standard (IS), liquid-liquid extraction with basified plasma using a mixture hexane/acetate (1:1, v/v) as the extracting solvent, and the final extract reconstituted in the mobile phase. I and II (IS) were injected in a C8 column with the mobile phase composed of methanol:isopropanol:water:formic acid (78.00:19.92:2.00:0.08, v/v/v/v) and monitored using a positive electrospray source with tandem mass spectrometry analyses. The selected reaction monitoring (SRM) was set using precursor ion and product ion combinations of m/z 256.0>167.0 and m/z 325.0>109.0 for I and II, respectively. The limit of quantification (LOQ) was 0.4 ng/mL, the dynamic range being 0.4-200 ng/mL. Validation results on linearity, specificity, accuracy, precision and stability, as well as on application to the analysis of plasma samples taken up to 24 h after oral administration of 100 mg of dimenhydrinate in healthy volunteers demonstrated its applicability to bioavailability studies.     

Determination of phloroglucinol in human plasma by high-performance liquid chromatography-mass spectrometry

A sensitive and selective liquid chromatographic method coupled with mass spectrometry (LC-MS) was developed for the quantification of phloroglucinol in human plasma. Resorcinol was used as internal standard, with plasma samples extracted using ethyl acetate. A centrifuged upper layer was then evaporated and reconstituted with mobile phase. The reconstituted samples were injected into a C(18) XTerra MS column (2.1 x 100 mm) with 3.5-microm particle size. The analytical column lasted for at least 500 injections. The mobile phase was 15% acetonitrile (pH 3.0), with flow-rate at 200 microl/min. The mass spectrometer was operated in negative ion mode with selective ion monitoring (SIM). Phloroglucinol was detected without severe interferences from plasma matrix when used negative ion mode. Phloroglucinol produced a parent molecule ([M-H](-)) at m/z 125 in negative ion mode. Detection of phloroglucinol in human plasma was accurate and precise, with quantification limit at 5 ng/ml. This method has been successfully applied to a study of phloroglucinol in human specimens.     

Rapid and sensitive determination of vinorelbine in human plasma by liquid chromatography-tandem mass spectrometry and its pharmacokinetic application

Vinorelbine is a semi-synthetic vinca alkaloid with demonstrated high activities against various types of advanced cancer. To support a clinical pharmacokinetic study, a simple, rapid and sensitive method to determine vinorelbine in human plasma was developed using reversed phase liquid chromatography (LC) coupled with electrospray ionization mass spectrometry/mass spectrometry (ESI-MS/MS). Vinorelbine and vinblastine (the internal standard) were extracted from human plasma by one-step liquid-liquid extraction (LLE) with methyl-t-butyl ether. The chromatographic separation was achieved on a Spursil polar-modified C(18) column (50 mm×2.1 mm, 3 μm, Dikma Technologies) with an isocratic mobile phase of a 75:25 (v/v) acetonitrile-4 mmol/L ammonium formate (pH 3.0) mixture at a flow-rate of 0.4 mL/min. The MS/MS detection was performed in the positive ion multiple reaction monitoring (MRM) mode by monitoring the precursor→product ion transitions at m/z 779.4→122.0 and m/z 811.3→224.2 for vinorelbine and the internal standard, respectively. The assay was validated in the range 0.1-200 ng/mL (r>0.997), the lowest level of this range being the lower limit of quantification (LLOQ) based on 50 μL of plasma. The intra- and inter-day precisions were within 6.0%, while the accuracy was within ±4.7% of nominal values. Detection and quantification of both analytes within 2 min make this method suitable for high-throughput analyses. The method was successfully applied to evaluate the systemic pharmacokinetics of vinorelbine after a 20-min intravenous infusion of 25 mg/m(2) of vinorelbine to patients with metastatic breast cancer.